Implantable medical systems that are designed to deliver electrical stimulation, for example, to cardiac muscle or the spinal cord, and/or to monitor bodily electrical activity, typically include a relatively compact implantable device to which one or more elongate implantable electrical leads are coupled, for example, like the exemplary system 10 schematically shown in FIG. 1A. FIG. 1A illustrates system 10 including an implantable defibrillator device 500 and a defibrillation lead 100, which is connected to device 500 and extends transvenously therefrom, into a heart of a patient, such that a defibrillation electrode 11 and a pace-sense electrode 13 of lead 100 are located in the right ventricle RV of the heart. Those skilled in the art appreciate that a power source and circuitry of device 500 are contained in a hermetically sealed housing 55 of device 500, which housing 55, being formed from a conductive metal such as titanium, may function as an electrode, in concert with electrode 11, to deliver high voltage pulses for defibrillation therapy in response to a cardiac arrhythmia, for example, sensed by electrodes 13, 11.
FIG. 1A further illustrates device 500 including a connector module 51 that has a port 501 into which a connector terminal 15 of lead 100 is inserted for electrical coupling with the circuitry contained in housing 55, for example, via electrical contacts, which are mounted within port 501 and coupled to the circuitry via hermetically sealed feedthroughs. Suitable constructions for such a connector module and lead connector are known to those skilled in the art. With reference to FIG. 1B, an outer insulation sheath 12 of lead 100 contains a first elongate conductor that couples electrode 11 to a first connector terminal contact 151, and a second elongate conductor that couples electrode 13 to a connector terminal contact pin 153. Typically each of electrodes 11, 13 are joined to the corresponding conductor via a crimp and/or weld joint that may include a separate coupling component. But, to simplify lead construction and/or to streamline a profile of the lead by eliminating at least one joint, it has been proposed that a coiled conductor include an integral electrode length that extends distally out from outer insulation sheath 12 to form electrode 11. Improvements on such a construction are desired, for example, to enhance lead performance in a system such as system 10.